Rocket fin assembly



March29, 1949. A. SKINNER 2,465,401

ROCKET FIN ASSEMBLY I Filed Sept. 25, 1943 Patented Mar. 29, 1949 UNITED STATES PATENT OFFICE (Granted under the act of March 3, 1883, as amended April 30, 1928; 370 0. G. 757) 12 Claims.

The invention described herein may be manufactured and used by or for the Government for governmental purposes, without the payment to me of any royalty thereon.

This invention relates to rocket projectiles, and more particularly, to the tail fins provided thereon to stabilize their flight. The prime object of invention is to devise a tail fin assemblage for rocket projectiles the blades of which are readily folded in ineffective position so as to ofier no protrusion to the passage of the projectile through the gun barrel but which are automatically turned by the rocket blast to their efiective position protruding radially from the projectile as the projectile leaves the gun barrel.

For the attainment of this and such other objects which may appear herein or be pointed. out I have shown an embodiment of my invention in the accompanying drawing, wherein:

Fig. 1 is a sectional elevation through the port end of a rocket projectile showing the tail fin assembly with their blades in ineffective position.

Fig. 2 is likewise a sectional elevation of the rear portion shown in Fig. 1, with the blades in effective, protruding position.

Fig. 3 is an end elevational view of the fin assemblage, showing principally the main supporting member or spider.

Fig. 4 is a sectional elevation through the spider, taken on the line 4-4 of Fig. 3.

Fig. 5 represents one of the blades of the fin assemblage.

Fig. 6 is an end elevational view of a retainer ring associated with the tail fin assemblage.

Fig. '7 is a sectional elevation through the retainer ring taken on the line |l of Fig. 6.

The tail fin assemblage comprises an annular spider Ill, a plurality of blades pivotally mounted on the spider, and a retainer ring 30. The spider l0 which constitutes the main supporting member of the assemblage, is an annular ring of the irregular section shown best in Fig. 4. This irregular sectional shape of the annular spider forms two annuli of different diameter. The annulus I I of smaller diameter is secured in any suitable manner in a groove I provided at or near the rear edge of the rocket port 9. The annulus l2 of larger diameter extends somewhat to the rear, Figs. 1 and 2, of the port edge, and is preferably internally rounded, as shown, as is the port 9, to offer less resistance to the effiux of gases. The portion of the annular spider connecting the securement annulus H of smaller diameter and the efilux annulus l2 of larger diameter forms a huh I 3 in which are provided a plu- 2 rality of slots I4 equidistanced from each other, to accommodate the same number of blades. Six such slots are shown in Fig. 3 for illustrative purposes, as the number of blades may be less or more than this number.

The blades 20 are provided with a small aperture 25, Fig. 5, through which is passed a pin [5 for pivotally mounting the blades in the hub slots I l. The blades are made of the proper width and length to permit them to nestle in the annular space surrounding the narrowed neck 8 at the rear of thebody I of the projectile. When the blades are nestled in ineffective position, as shown in Fig. 1, they present no part protruding beyond the projectile body 1, as the projectile passes through the gun barrel. The distal edges of the blades, Fig. 5, are beveled 26, to conform with the sloped shoulder 6 between the projectile neck 8 and body I.

The distal edges of the blades are beveled, 26, Fig. 1, not only to conform to the sloped shoulder 6 of the projectile, but also to provide for the turning of the blades outwardly to effective position upon the discharge of the rocket. As the projectile is shot through the gun barrel a considerable air flow is created, suflicient of which flows between the beveled blade end 26 and the projectile shoulder 6 to give rise to a force which acts in a direction more or less normal to bevel edge 26 to turn the blade outwardly about its pivot pin l5. Also, the beveling of distal edge 26 gives the blade an unsymmetrical outline with the larger area disposed outwardly relative to the center line of the projectile, so that the center of gravity of the blade will be somewhat nearer to the outer and longer side of the blade than to the inner and shorter side: i. e., the center of gravity of the blade will be disposed somewhat outwardly of a line passing through the pivotal point l5 parallel to the projectile axis. As the projectile is discharged, the inertia of the blade acting on the said displaced center of gravity will turn the blade outwardly on its pivotal point l5.

Additionally, blow holes 5, Fig. 1, may be provided in the rocket, neck 8 in alignment with blades 20, to enable a small blast of gas to turn the blades to open position upon discharge of the rocket projectile.

A retainer ring 30, detailed in Figs. 6-7, is provided for the purpose of holding the blades in retracted, inefiective position during loading and handling of the pro ectile. Retainer ring 30 is fabricated of sheet material in annular dished form as clearly seen in Fig. 1 with the edge of its flange 3| slightly turned outwardly to form a number of scallops 32 equal to the number of blades. The edge of flange 3|, more particularly, its scalloped portions 32, cooperate with a lip 22 formed at the proximal end of the blades. As best seen in Fig. 1, the blade lip 22 is so positioned that whenv the: retainer ring 38 in, effective position, as shown in Fig. 1, its scalloped flange end is received in underlying relation to the lip 22 to hold the blade in retracted position as shown in Fig. 1. The retainer ring is placed in its effective blade-holding position by inserting the retainer ring so that its flange proper, rather than the scalloped portions, will underlie the lips of the blades; the retainer ring is then turned; to spring press, against the resiliency of the sheet material of the ring, more particularly, its flange, the scallops under the blade lips. To facilitate this turning of the retainer ring, its inner edge may be provided with a pair of opposed notches 33 to: receive an appropriate tool. The retainer ring is blown on by the rocket blast, to permit the blades. to be. turned to open or effective position, upon discharging the gun. For this reason the retainer ring is made sufficiently wide to present a portion, designated 35 in Fig. I, protruding in the path of the. rocket blast.

I claim:

In a tail fin assemblage for a rocket projectile having a reduced discharge necl: joined to the projectile body in a sloped shoulder, in combinati'on, an annular spider having two annuli of dif-= feren-t diameter joined by a hub. portion, the

annulus of small diameter being secured in a circumferential groove provided at the rocket port toposition the annulus of larger diameter beyond the rocket port, the said larger annulus being internally rounded, a plurality of blades having an aperture at one end, the hub portion of the spider being provided with a plurality of equid'istanced slots to'receivethe said blades, pin means hingedly securing the blades at their said apertures, the distal end of the blades being sloped in substantiaF conformance with the. said sloped shoulder of theprojectile sothat the blades are nestled in their ineffective-position in the annular space surrounding the said discharge neck to present no protrusion beyond the outside diameter of the. projectile body, the said discharge neck beingprovided with a pluralityof line apertures aligned with the said blades to enable the rocket blast to turn the blades to eifective-position, and a retainer ring having an annular body portion flanged along itsouter edge, the said flange being provided with a plurality of turned-up scallops, the apertured end of the bladesbei'ng provided with a cut-out portion presenting a lip, the outside radius of the said retainer flange being less than the radial distance to the said blade lip when the blade is in ineffective position, whereby the retainer ring may he slipped over the rocket port with the blade lips positioned between the retainer scallops, the radius of the scallopsbeing greater than that of the retainer flange whereby the scallops will securely engage the said blade lips upon turning the said retainer ring, the inner edge of the said annular body portion of the retainer being provided: with a pair of opposed tool notches, and the said annular body portion being sufliciently wide to pre-ent an inner portion to the rocket blast.

2. In a tail fin as-emblage for a rocket projectile having a reduced discharge neck joined to the. projectile body in a sloped shoulder, in combination, an annular spider having two annuli. of different diameter joined by a hub. portion, the

annulus of small diameter being secured at the rocket port to position the annulus of larger diameter beyond the rocket port, the said larger annulus being internally rounded, a plurality of blades having an aperture at one end, the said hub portion of the spider being provided with a plurality of equidistanced slots to receive the said blades, pin means hingedly securing the blades at their said apertures, the distal end of the blades being sloped in substantial conformance with the said sloped shoulder of the projectile so that the blades are nestled in their ineffective position in the annular space surrounding the said discharge neck to present no protrusion beyond the outside diameter of the projectile body, the said discharge neck being provided with a plurality of hue apertures aligned with the said blades to enable the rocket: blast to turn the blades to effective position, and a retainer ring having an annular body portion flanged along its outer edge, the said flange being provided with a plurality of turnedup scallops, the apertured end of the blades being provided with a cut-out portion presenting a lip, the outside radius of the said retainer flange being less than the radial di:tance to the said blade lip when the blade is in ineffective position, whereby the retainer ring may be slipped over the rocket port with the blade lips positioned between the retainer scallops, the radius of the scallops being greater than that of the retainer flange whereby the scallops will securely engage the said blade lips upon turning the said retainer ring, the inner edge of the said annular body portion of the retainer being provided with a pair of opposed tool notches, and the said annular body portion being sufficiently wide to present an inner portion to the rocket blade.

3. In a tail fin assemblage for a rocket projectile having a reduced discharge neck joined to the projectile body in a sloped shoulder, in combination, an annular spider having two annuli of diflerent diameter joined by a hub portion, the annulus of small diameter being secured at the rocket port to position the annulus of larger diameter beyond the rocket port, a plurality ofblades having an aperture at one end, the said hub. portion of the spider being provided with a plurality of equidistanced'sl'ots to receive the said blades, pin means hingedly securing the blades at their said apertures, the distal end of the blades being sloped in substantial conformance With the said sloped shoulder of th projectile so that the blades are nestled in their ineffective position in the annular space surrounding the said discharge neck to present'no protrusion beyond the outside diameter of the projectile body, the said discharge neck being provided with a plurality of fine apertures, aligned with the said blades to enable the rocket blast to turn the blades to effective position, and a retainer ring having an annular body portion flanged along its: outer edge, the said flange being provided with a plurality of turned-up scallops, the apertured end of the blades being provided with a cut-out portion presenting a lip, the outside radius of.

lops, the radius of the scallops being greater than that of the retainer flange whereby the 1 scallops will securely engage the said blade lips upon, turning the said retainer ring, the inner.

edge: of the said, annular body portionv off the retainer being provided with a pair of opposed tool notches, and the said annular body portion being sufliciently wide to present an inner portion to the rocket blast.

4. In a tail fin assemblage for a rocket projectile having a reduced discharge neck joined to the projectile body in a sloped shoulder, in. combination, an annular spider having two annuli of diiferent diameter joined by a hub portion, the annulus of small diameter being secured at the rocket port to position the annulus of larger diameter beyond the rocket port, a plurality of blades having an aperture at one end, the said hub portion of the spider being provided with a plurality of equidistanced slots to receive the said blades, pin means hingedly securing the blades at their said apertures, the distal end of the blades being sloped in substantial conformance with the said sloped shoulder of the projectile so that the blades are nestled in their ineffective position in the annular space surrounding the said discharge neck to present no protrusion beyond the outside d ameter of the projectile body, the said discharge neck being provided with a plurality of fine apertures aligned with the said blades to enable the rocket blast to turn the blades to efiective position, and a retainer ring having an annular body port on flanged along its outer edge, the said flange be ng provided with a plurality of turned-up scallops, the apertured end of the blades being provided with a cut-out portion present ng a lip, the outside radius of the said retainer flange being less than the radial distance to the said blade lip when the blade is in inefiective position, whereby the retainer ring may be s ipped over the rocket port with the blad lips positioned between the retainer scallops, the radius of the scallops being greater than that of the retainer flange whereby the scallops will securely engage the said blade lips upon turning the said retainer ring, and the said annular body port on being suflicient y wide to present an inner portion to the rocket blast.

5. In a tail fln assemblage for a rocket pro ectile having a reduced discharge neck joined to the projectile body in a sloped shoulder, in comb nation, an annular spider having two annuli of difierent diameter joined by a hub port on. the annulus of small d ameter being secured at the rocket port to position the annulus of lar er diameter beyond the rocket port, a plurality of blades hav ng an aperture at one end. the sa d hub ortion of the spider be ng prov ded with a p u ality of equidistanced slots to receive the said blades, pin means hingedly secur ng the blades at their said apertures. the distal end of the bla es being slo ed n sub tant al conformance with the sa d sloped shoulder of the projectile so that the b ades are nestled in the r-ineffect ve position in the annular space surrounding the said dis har e neck to present no protrusion bevond the out i e diameter of the project le body, the sa d discharge neck being provid d w th a p a itv of fine apertures a i ned with the sa d blades to enab e the rocket blast to turn the b ades to efiective osit on, and a retainer ring hav ng an annular bo y portion flan ed alon its outer edge. the said flange be ng p ovided w th a lural ty of turne -up sca lops. the a e tured e d of t e blades be n p ovided with a l p the ou ide rad us of t e said reta ner flan e being less than the radial d st nce to the sa d blade 1 w n th b d i n i f ctive po ition, whereb t e retainer ring may be sl pped over the rocket port with the blade lips positioned between the retainer scallops, the radius of the scallops being greater than that of the retainer flange whereby the scallops will securely engage the said blade lips upon turning the said retainer ring, and the said annular body portion being sufl'iciently wide to present an inner portion to the rocket blast.

6. In a tail fin assemblage for a rocket projectile having a reduced discharge neck joined to the projectile body in a sloped shouder, in combination, an annular spider secured at the rocket port of the said reduced discharge neck, a plurality of blades having an aperture at one end, the said spider being provided with a plurality of equidistanced slots to receive the said blades, pin means hingedly securing the blades at their said apertures, the distal end of the blades being sloped in substantial conformance with the said sloped shoulder of the projectile so that the bades are nestled in their ineffective position in the annular space surrounding the sa d discharge neck to present no protrusion beyond the outside diameter of the projectile body, the said discharge neck be ng provided with a plurality of fine apertures aligned with the said blades to enable the rocket blast to turn the blades to effective position,

and a retainer r ng having an annular body portion flanged along its outer edge. the said flan e being provided with a plurality of turned-up scallops, the apertured end of the blades being provided with a lip, the outside radius of the said retainer flange being less than the radial distance to the said bade lip when the blade is in ineffective position, whereby the retainer ring may be slipped over the rocket port with the blade lips positioned between the retainer scallops, the radius of the scallops, being greater than that of the retainer flange whereby the scallops will securely engage the said blade lips upon turning the said retainer ring, and the said annular body portion being suificiently wide to present an inner portion to the rocket blast.

7. In a tail fin assemblage for a rocket projectile having a reduced discharge neck joined to the projectile body in a sloped shoulder, in combination, an annular spider secured at the rocket port of the said reduced discharge neck, a plurality of blades having an aperture at one end, the said spider being provided with a plurality of equidistanced slots to receive the said blades, pin means hingedly securing the blades at their said apertures, the distal end of the blades being sloped in substantial conformance with the said sloped shoulder of the projectile so that the blades are nestled in their inefiective position in the annular space surrounding the said discharge neck to present no protrusion beyond the outside diameter of the projectile body, the said discharge neck being provided with a plurality of fine apertures aligned with the said blades to enable the rocket blast to turn the blades to efiective position, and a retainer ring adapted to be slipped over the rocket port to hold the said blades in their said inefiective position, and presenting an annular portion to the rocket blast.

8. In a tail fin assemblage for a rocket projec" tile having a reduced discharge neck, in combination, an annular spider secured at the rocket port, a plurality of blades having an aperture at one end, the said spider being provided with a plurality of equidistanced slots to receive the said blades, pin means hingedly securing the blades at their said apertures to the said spider so that the blades are nestled in their inefiective position in the annular space surrounding the said discharge neck to; present; no protrusion beyond the outside diameter of the projectile body, the said discharge neck. being provided with! av plurality of fine apertures aligned with the said blades to enable the rocket; blast to turn the blades to effective position, anda retainer ring adapted to he slipped over the rocket port to hold the said blades intheir said ineffective position, and presenting an annular portion tothe rocket blast.

9. In a tail fin assemblage-for a rocket projectile having a reduced-discharge neck, in combination, an annular spider secured at the rocket port ot the said reduced neck, a plurality of blades hingedly secured on the said spider and adapted to nestle in their ineifective position in the: annular space surrounding the saiddischarge neck topresent no protrusion beyond the outside diameter of the projectile body, the said discharge neck being provided with a plurality of fine apertures aligned with the said blades to enable the rocket blast to turnthe blades to effective position, and a retainer ring for holding the: said blades in their said inefiective position, the said retainer ring presenting a portion thereofto the rocket blast. whereby the said retainer ring isblown ofi upon discharge of the projectile.

10. In a tai-lfin assemblage for a rocket projectile having a reduced discharge neck, in. combination, an annular spider secured at the rocket port of thesaid reduced neck, a plurality of blades hingedly secured on the said spider and adapted to nestle in their inefiective position in the annu.--

lar space surrounding the said. discharge neck 8: to present naprotrusion: beyond the outside di-anv eter of the; projectile body,, a retainer ringI for holding the said blades in their said ineffective position, and means utilizing the rocket blast for releasing thesaid-retainer ringand for turning the blades to effective position.

11-, In combination a rocket projectile having; hinged ta-i-l. fins and means for holding, said finsin, closed. position comprising ari-ng member having. camimeans for engagement with a portion, oi the fins to: retain said fins in= ineffective position, said'ring. member being cup shaped and-said cam means comprising outward dentsin the sides of said member.

12'. In combination: a rocket: projectile having hinged tail fins and means for holding said fins in: closed position comprising a ring member, said. ring member being. cup shaped and having a bottom portion being dimensioned to lie in the, blast of the rocket gases, said; blast disengaging said member from said fins to permit said fins to be turned to'open or efiective position.

A. SKINN-ER.

REFERENCES CITED The following references are of record in the" me of this patent:

UNITED STATES PATENTS 

